In the context of the question, urine is a liquid waste product excreted by the kidneys. Let's go through each option to determine which one should not be present in urine:
a. Water: Urine should contain water as it is the main component that helps to dissolve waste products and carry them out of the body. So, water should be present in urine.
b. Electrolytes: Electrolytes are essential minerals like sodium, potassium, and chloride that help maintain the body's balance of fluids. These are normally found in urine to some extent, so electrolytes should be present.
c. Red blood cells: Red blood cells are not typically present in urine under normal circumstances. Their presence in urine could indicate a potential medical issue like kidney damage or infection. Therefore, red blood cells should not be present in urine.
d. Urea: Urea is a waste product formed in the liver as a result of protein metabolism and is excreted in urine. It is a normal component of urine and should be present.
Based on the above explanations, the correct answer to the question is:
c. Red blood cells.
